There are many transceivers in the prior having single-element antennas, such as GPS devices, for example. GPS devices can often include single-element antenna elements because of cost and size constraints. Other platforms which can include single-element antennas can include UUV's and UAV's and small maritime platforms. These types of platforms have extremely constrained antenna footprints, and space for these antennas is at a premium. The resulting received signals from such GPS devices and such platforms can be extremely weak and corrupted by interference. The resulting transmitted signals from such platforms may be weak in desired directions. One way to “boost” the reception power of such devices is to employ phased array antennas that have multiple receiving/radiating elements, such as Controlled Reception Pattern Antennas (CRPA). But these types of systems can often require more space than that allotted for the platform. Additionally, the control requirements, costs, and electronics to drive the multiple elements for such antennas can be unduly burdensome to the platform. On the other hand, legacy systems employing a single-element antenna such as a Fixed Reception Pattern Antenna (FRPA) antenna are susceptible to interference.
As mentioned above, beam steering can be generally accomplished with multiple element phased-arrays. Recently, there has been some interest in making active (or beam-steering) radomes using metamaterials. Such radomes take advantage of the phenomena caused by wave interaction due to passing the RF through a thick radome made of metamaterials. However, these techniques can place a strong dependency on the radome material, which imposes certain requirements such as attenuation, frequency response, weight and size. With regard to weight and size in particular, the use of metamaterials for active radome beam steering may be a huge disadvantage for a small airborne platforms such as UAV's.
In view of the above, it is an object of the present invention to provide an active radome that allows for beam steering and nulling, with potentially multiple beams or nulls, with a single element for radiating or receiving radiofrequency (RF) energy, which results in a more agile single-element GPS antenna or other receiving or transmitting antenna. Another object of the present invention is to provide an active radome with the employed switched conducting elements, such that a thick slab for the radome is not required, while still achieving the desired wave changes (beam steering/nulling). Still another object of the present invention is to provide an active radome with conductive switching elements rather than metamaterials, which may result in an improved frequency response for the overall antenna, while significantly reducing the radome attenuation, weight and size properties, which are of great concern on mobile platforms. Another object of the present invention is to provide an active radome that mitigates interference affecting an existing antenna by effectively using minimal resources and without the need to replace the antenna. Still another object of the present invention is to provide a radome for a single-element antenna that provides directionality for that antenna within a confined space. Yet another object of the present invention is to provide an active radome that can be adapted to be back-fit over an existing antenna, along with circuitry that adaptively controls the various elements in the radome. Another object of the present invention is to provide an active radome that is easy to manufacture in a cost-effective manner.